Islam has been around forever, since the creation of our world and the first humans, Adam and Hawa (Eve). People like Noah, Moses, Abraham, Joseph, are all said to be muslims and are prophets in Islam. However Islam is often datated to appear 1400 years ago when the Qu'ran was revealed to Muhammad. This is because the teachings of Islam are very similar to other religions like Christianity and Judaism, but the belief is that those religions have some ideas that have taken away from the real religion, such as the idea of the trinity. The Qu'ran was given as guidance.
Islam emerged in the 7th century AD, springing full-formed from the head of Muhammad bin Abdullah.